1. Field of the Invention
This invention relates to an infusion pump apparatus and method wherein small amounts of concentrated medication are mixed and diluted with a carrier prior to being released into the patient. The use of a concentrated medication which is diluted will reduce the required size of the pump and the frequency of a patient's refill visits.
2. Discussion of the Related Art
Implantable access ports and drug infusion pumps are well known in the art. For example, U.S. Pat. No. 5,792,104 to Speckman et al. and U.S. Pat. No. 5,833,654 to Powers et al. both disclose dual reservoir access ports. However, the ports of both Speckman and Powers are designed so that the contents of the reservoirs are never mixed, either internal or external to the ports. Both Speckman and Powers disclose attachment means and dual lumen catheters that are designed to keep the contents of the reservoirs separate until the catheter discharges into the patient. Thus, neither Speckman nor Powers allows for the contents of the reservoirs to be mixed prior to discharge to the patient.
Tucker et al. in U.S. Pat. Nos. 4,193,397 and 4,258,711 (hereinafter “Tucker”) disclose a dual reservoir implantable pump with an accumulator. Tucker further discloses a basal reservoir containing medication of a certain dosage and a smaller bolus reservoir containing high concentrate medication. The basal reservoir discharges medication to the patient at a specified rate. The basal reservoir discharges the high concentration of medication to a smaller accumulator and, at a specified time, the accumulator discharges the bolus dose into the basal medication discharge. However, Tucker's bolus dose is never mixed and diluted with the basal dose. The bolus dose is sent as a short ‘burst’ of medication at timed or triggered intervals. Additionally, both the basal and the bolus reservoirs contain medication that must be refilled by a doctor.
Thus, there is a need in the art for an implantable infusion device that mixes and dilutes a non-medication carrier with concentrated medication to reduce the size of the device. Additionally, diluting a concentrated medication with a carrier allows a patient to refill his/her own carrier reservoir multiple times before the medication reservoir requires refilling. This reduces the number of times a patient must visit a doctor to refill the medication reservoir.